O. Riera-lizarazu et al., Production and characterization of maize chromosome 9 radiation hybrids derived from an oat-maize addition line, GENETICS, 156(1), 2000, pp. 327-339
In maize (Zea mays L., 2n = 2x = 20), map-based cloning and genome organiza
tion studies are often complicated because of the complexity of the genome.
Maize chromosome addition lines of hexaploid cultivated oat (Avena sativa
L., 2n = 6x = 42),where maize chromosomes can be individually manipulated,
represent unique materials for maize genome analysis. Maize chromosome addi
tion lines are particularly suitable for the dissection of a single maize c
hromosome using radiation because cultivated oat is an allohexaploid in whi
ch multiple copies of the oat basic genome provide buffering to chromosomal
aberrations and other mutations. Irradiation (gamma rays at 30, 40, and 50
krad) of a monosomic maize chromosome 9 addition line produced maize chrom
osome 9 radiation hybrids (M9RHs)-oat lines possessing different fragments
of maize chromosome 9 including intergenomic translocations and modified ma
ize addition chromosomes with internal and terminal deletions. M9RHs with 1
to 10 radiation-induced breaks per chromosome were identified. We estimate
d that a panel of 100 informative M9RHs (with an average of 3 breaks per ch
romosome) would allow mapping at the 0.5- to 1.0-Mb level of resolution. Be
cause mapping with maize chromosome addition lines and radiation hybrid der
ivatives involves assays for the presence or absence of a given marker, mon
omorphic markers can be quickly and efficiently mapped to a chromosome regi
on. Radiation hybrid derivatives also represent sources of region-specific
DNA for cloning of genes or DNA markers.